Here are a few possibilities, but they aren't exactly household names:
* Ulysses S. Grant: While he was born in Ohio, Ulysses S. Grant spent part of his youth in Texas and later served in the Texas Army. He is most known as the 18th President of the United States.
* Umberto Eco: Although not born in Texas, the Italian writer Umberto Eco lived in Austin, Texas for several years. He is known for his novels such as "The Name of the Rose" and "Foucault's Pendulum."
It's important to remember that "famous" is subjective. There could be many talented, successful individuals from Texas with last names starting with "U," but they might not have achieved the same level of national or international recognition.
If you're interested in learning more about specific fields or industries, we could try to find some "U" names within those areas. For example, are you looking for actors, musicians, athletes, politicians, scientists, or someone else?